A sexual fetish involving a fascination with mermaids often to the point of being borderline erotic; a mermaphile
2. one who is sexually fixated on mermaid related paraphernalia i.e. costumes, drawings books poems, styles, clothing, etc.
3. A variation of aquaphilia where said person will have sex in pools, lakes, rivers or any large body of water.

Ariel: my boyfriend is such a mermaphile,ever since I told him my name, he won't have sex with me unless I dress up in a mermaid's tail!